CN111087701B

CN111087701B - Antibacterial polypropylene composition, microporous antibacterial polypropylene foamed sheet, preparation method of microporous antibacterial polypropylene foamed sheet and foamed sheet

Info

Publication number: CN111087701B
Application number: CN201811239584.2A
Authority: CN
Inventors: 徐耀辉; 吕明福; 郭鹏; 初立秋; 李�杰; 张师军; 邵静波; 吕芸; 侴白舸; 白弈青
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2018-10-23
Filing date: 2018-10-23
Publication date: 2022-11-18
Anticipated expiration: 2038-10-23
Also published as: CN111087701A

Abstract

The invention belongs to the field of antibacterial materials and products thereof, and discloses an antibacterial polypropylene composition, a microporous antibacterial polypropylene foamed sheet, a preparation method of the microporous antibacterial polypropylene foamed sheet and a foamed sheet. The antibacterial polypropylene composition contains polypropylene base resin, a guanidine salt composite antibacterial agent and an auxiliary agent, wherein the auxiliary agent contains a foam cell nucleating agent and an antioxidant, the content of the guanidine salt composite antibacterial agent is 0.05-2.0 parts by weight, the content of the foam cell nucleating agent is 0.01-10 parts by weight, and the content of the antioxidant is 0.01-10 parts by weight based on 100 parts by weight of the polypropylene base resin. The foaming plate/sheet prepared by the invention has the characteristics of easy slicing, excellent mechanical property, antibiosis, simple and convenient preparation process, large adjustable range of multiplying power, good heat preservation performance and the like.

Description

Antibacterial polypropylene composition, microporous antibacterial polypropylene foamed sheet, preparation method of microporous antibacterial polypropylene foamed sheet and foamed sheet

Technical Field

The invention belongs to the field of antibacterial materials and products thereof, and particularly relates to an antibacterial polypropylene composition, a microporous antibacterial polypropylene foamed sheet, a preparation method of the microporous antibacterial polypropylene foamed sheet, and a microporous antibacterial polypropylene foamed sheet.

Background

The polypropylene foaming material has excellent heat resistance, insulativity, heat preservation, cold resistance, oil resistance, chemical resistance and barrier property, and is easy to recycle. Therefore, compared with the expanded polystyrene (EPS or XPS) or Expanded Polyurethane (EPU) which is common in the market at present, the polypropylene foaming material has a very wide development and application prospect, can be applied to heat-insulating layers for logistics cold chain transportation, heat-insulating layers for automobile, passenger car and rail transit vehicle armrest ceiling floors, heat-insulating layers for inner and outer walls of buildings and the like, and even in the occasions where people in daily life closely contact such as bathrooms, household appliances and toys for children and the like, the polypropylene foaming material with different performances is tried to be used to replace the existing metal and plastic plate sheets. Thereby reducing material cost, lightening construction strength, increasing service time, reducing energy consumption of working environment and the like. The daily life is applied in a humid environment, and bacteria and mould are easy to breed, so that the development of antibacterial high-performance lightweight materials is increasingly becoming a hot field for the development and research of functional polypropylene materials.

The preparation of the antibacterial plastic is mainly to uniformly mix the matrix resin, the antibacterial agent and the process aid according to a certain proportion, then directly melt and blend to prepare the modified resin with the antibacterial function, and finally manufacture various antibacterial products by various plastic molding processing methods (such as extrusion, injection molding, casting, blow molding, plastic uptake and the like). Currently, the antimicrobial agents used in the market mainly include inorganic and organic antimicrobial agents. The inorganic antibacterial agent is mainly an inorganic substance loaded with antibacterial metal ions (such as one or more of silver ions, zinc ions, copper ions and the like), and can be used for a variety of loaded carriers, including zeolite (natural or synthetic zeolite), zirconium phosphate, soluble glass, calcium phosphate, silica gel and the like. The organic antibacterial agents are classified according to their structures, and include quaternary ammonium salts, quaternary phosphonium salts, imidazoles, pyridines, organic metals, and the like. The inorganic antibacterial agent has the characteristics of high safety, good heat resistance, durable sterilization and the like, but the sterilization of the inorganic antibacterial agent is not immediate, and the price of the inorganic antibacterial agent is high due to the adoption of noble metals. The organic antibacterial agent has the advantages of high sterilization speed, good antibacterial effect, wide application range and the like, but has the problems of easy generation of drug resistance, poor heat resistance and the like.

The guanidine salt polymer is an antibacterial polymer with a guanidyl group in a molecular structure, is a novel broad-spectrum, efficient, nontoxic and nonirritating antibacterial product developed in the nineties of the last century, and is widely applied to the fields of textile, agriculture, food, sanitation and the like. Currently, the variety of guanidine salt polymers mainly includes polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine propionate, polyhexamethylene (bis) guanidine stearate, and other inorganic or organic salts of polyhexamethylene (bis) guanidine, polyoxyethylene guanidine, and the like.

Guanidine salt polymers are mostly used in the form of aqueous solutions due to their excellent solubility in water, and are used as bactericides for water treatment in patent documents JP05209195, US4891423, CN 101156586A. Compared with other organic antibacterial agents, the guanidine salt polymer has good thermal stability and high thermal decomposition temperature up to 280 ℃, so that the guanidine salt polymer can be used as an antibacterial additive to be applied to plastic, fiber and rubber products to obtain antibacterial products. However, most guanidinium polymers are very water soluble, making powder samples difficult, limiting their use in plastic, rubber, and fiber applications. Patent document CN101037503A discloses a method for preparing a powdered guanidine salt polymer product, wherein a guanidine salt polymer is separated from an aqueous solution through an ion separation exchange membrane to prepare a powder sample.

Patent documents CN1350022A, CN1445270A and US7282538B2 disclose a method for preparing polyamine and guanidinium polymer, wherein the guanidinium polymer contains double bonds, epoxy and other active groups in the molecular structure, and is used for carrying out melting, solution and solid phase grafting reaction with resin polymer to prepare antibacterial plastic products. Patent documents CN102453315A, CN102453316A and CN102286176A prepare composite antibacterial agents by coprecipitation of guanidine salt polymers and pyridine sulfate, silicate, etc., and apply the composite antibacterial agents to film products such as polypropylene and polypropylene, and foam plastic products. It can be seen from the above patent documents that the conditions for preparing guanidine salt polymer powder in CN101037503A and CN1350022A are harsh and the process is complicated; in patent documents CN1445270A and US7282538B2, guanidine salt polymers need to be prepared into antibacterial master batches, which is complicated in steps and high in cost; in patent documents CN102453315A and CN102453316A, sodium pyrithione needs to be used, which is costly; CN102453273A needs to be operated at a certain temperature in the process of preparing the antibacterial agent, so that the energy consumption is high, and the appearance and the particle size of the dried and crushed product are not well controlled.

At present, polypropylene foam molding with high magnification (more than or equal to 2 times) mainly comprises three methods, namely a kettle pressure foam secondary molding method, an extrusion foam method and a mould pressing foam method. The autoclave method comprises the steps of impregnating polypropylene microparticles with a foaming agent in an autoclave, rapidly releasing pressure and foaming to prepare polypropylene foamed particles with the particle size of about 2-4mm, and performing secondary heating molding in a mold, and has the advantages of high product foaming ratio (15-45 times) and capability of obtaining products with complex shapes. However, due to the limitation of the secondary forming mold, it is difficult to prepare a large-area plate from the EPP beads, and the plate is easily broken from the portion where the beads are adhered during cutting, so that a satisfactory sheet cannot be obtained.

The extrusion foaming method is to put polypropylene composition particles into an extruder, and melt-knead the particles using carbon dioxide, hydrocarbons, chemical foaming agents or crosslinking agents as needed under heat and pressure, and then extrude and foam the particles. However, the foamed sheet obtained by using carbon dioxide as a foaming agent has large diameter of cells (about 500 mu m), high aperture ratio (more than or equal to 50 percent), poor mechanical property and brittle material, and can not be cut into sheets; the foaming rate of the foaming plate obtained by using the chemical foaming agent is low (about 5 times), the weight is not obviously reduced, the shape of foam cells is not uniform, and the foaming plate is not easy to cut.

The mould pressing foaming method is that the polypropylene plate is put into a mould pressing machine, the foaming agent such as carbon dioxide is introduced, the temperature and the pressure are raised to ensure that the foaming agent is soaked and saturated in the plate, and then the pressure and the temperature are quickly released to prepare the foaming plate. It can be processed using a common hot press. Simple process equipment, mild conditions, low equipment requirement and low production cost. The foaming process has the advantages that after a mother board is extruded and molded, the supercritical fluid foaming agent can be fully impregnated in a mold, and the foaming plate with large surface area can be manufactured by one-step molding through rapid pressure relief and mold opening, wherein the amplitude can reach 2400mm multiplied by 1200mm. The foaming ratio is wide, 5 to 35 times of foaming material can be obtained by adjusting process conditions, and different application requirements are met. The foaming agent is fully saturated and impregnated in the production process of the mould pressing foaming method, and is uniformly dispersed in the polypropylene resin, so that the foaming agent can be used as a plurality of bubble heterogeneous nucleation points during pressure relief foaming, and the rapid and large-scale growth of cells is promoted instead of combination and enlargement. Therefore, the mould pressing foaming polypropylene material has a uniform and fine cellular structure with the diameter of less than 50 mu m, can be called as a microporous material, and brings more excellent mechanical property, heat preservation property and processing property to the foaming material. As the foamed polypropylene sheet is formed once, foam holes are uniform, fine and easy to cut, and a foamed sheet with the minimum thickness of 0.3mm and the tolerance of 0.01 can be obtained by cutting with a universal complete set of cutting tool, the foamed polypropylene sheet is the most ideal processing mode for the foamed polypropylene sheet at present.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention aims to provide an antimicrobial polypropylene composition, a microporous antimicrobial polypropylene foamed sheet, a method for preparing a microporous antimicrobial polypropylene foamed sheet, and a microporous antimicrobial polypropylene foamed sheet. The foaming plate/sheet prepared by the invention has the characteristics of easy slicing, excellent mechanical property, antibiosis, simple and convenient preparation process, large adjustable range of multiplying power, good heat preservation performance and the like.

The invention provides an antibacterial polypropylene composition, which comprises polypropylene base resin, a guanidine salt composite antibacterial agent and an auxiliary agent, wherein the auxiliary agent comprises a foam cell nucleating agent and an antioxidant, wherein the content of the guanidine salt composite antibacterial agent is 0.05-2.0 parts by weight, the content of the foam cell nucleating agent is 0.01-10 parts by weight and the content of the antioxidant is 0.01-10 parts by weight based on 100 parts by weight of the polypropylene base resin.

The second aspect of the present invention provides a microporous antibacterial polypropylene foamed sheet, which is prepared from the above antibacterial polypropylene composition.

The third aspect of the invention provides a preparation method of a microporous antibacterial polypropylene foamed sheet, which comprises the steps of granulating the antibacterial polypropylene composition, extruding the obtained antibacterial polypropylene particles into a sheet, and foaming, wherein the foaming method is preferably a mould pressing foaming method.

The fourth aspect of the invention provides a microporous antibacterial polypropylene foamed sheet, which is obtained by cutting and molding the microporous antibacterial polypropylene foamed sheet or the microporous antibacterial polypropylene foamed sheet prepared by the preparation method.

Compared with the prior art, the invention has the following beneficial effects:

(1) The guanidine salt composite antibacterial agent adopted by the invention has good fluidity and low moisture absorption, so that in the preparation process of the antibacterial polypropylene composition, the guanidine salt polymer is not adhered to the wall, the material is easy to discharge, the production operation is simple, and excessive production condition control is not needed; the prepared antibacterial polypropylene composition has good antibacterial effect and improved water resistance.

(2) The microporous antibacterial polypropylene foaming plate/sheet has the advantages of excellent antibacterial performance, excellent mechanical property, good thermal insulation performance, fine and compact sheet surface, tear resistance and the like due to the unique ultramicropore structure, so that the microporous antibacterial polypropylene foaming plate/sheet is suitable for military and civil fields with high comprehensive requirements on light weight, bacteria resistance and low-temperature impact resistance of products, such as daily home, automobile interior, medical appliances, aerospace and the like; the preparation methods of the antibacterial polypropylene composition and the foaming plate/sheet are simple, effective and easy to operate.

(3) The invention adopts carbon dioxide and/or nitrogen as the foaming agent, and has the advantages of environmental protection, safety and the like compared with the prior art which uses organic foaming agents.

(4) The foaming antibacterial polypropylene material prepared by the invention is of a non-crosslinked structure, can be recycled according to common polypropylene modified materials, does not cause secondary pollution, and meets the requirement of circular economy.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

FIG. 1: scanning electron microscope images of cross-sectional cells of the foamed sheet prepared in example 3 of the present invention.

FIG. 2: scanning electron microscope images of cross-sectional cells of the foamed sheet prepared in comparative example 1 of the present invention.

FIG. 3: scanning electron microscope images of cross-sectional cells of the foamed sheet prepared in comparative example 2 of the present invention.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are given by way of illustration and explanation only, not limitation.

According to a first aspect of the present invention, the present invention provides an antibacterial polypropylene composition, which comprises a polypropylene base resin, a guanidine salt composite antibacterial agent and an auxiliary agent, wherein the auxiliary agent comprises a foam cell nucleating agent and an antioxidant, wherein the guanidine salt composite antibacterial agent is 0.05 to 2.0 parts by weight, the foam cell nucleating agent is 0.01 to 10 parts by weight, and the antioxidant is 0.01 to 10 parts by weight, based on 100 parts by weight of the polypropylene base resin.

Preferably, the guanidine salt composite antibacterial agent is contained in an amount of 0.05 to 1.5 parts by weight, the foam cell nucleating agent is contained in an amount of 0.01 to 0.5 parts by weight, and the antioxidant is contained in an amount of 0.01 to 5 parts by weight, based on 100 parts by weight of the polypropylene base resin.

According to the present invention, the polypropylene base resin includes polypropylene or a mixture of polypropylene and other resins.

Wherein, the polypropylene can be homo polypropylene and/or random copolymerization polypropylene. Preferably, the random copolymerization polypropylene is selected from one or more of ethylene propylene random copolymerization polypropylene, propylene butadiene random copolymerization polypropylene, ethylene propylene butadiene random copolymerization polypropylene, block copolymerization polypropylene and impact copolymerization polypropylene.

Preferably, the polypropylene has a melt index MFR of 0.1 to 3g/10min at 230 ℃ under a load of 2.16kg, a molecular weight distribution Mw/Mn =4 to 20, and a polymer dispersion index of 5.0 to 16.0.

Further preferably, the polypropylene is a high melt strength polypropylene.

Specific examples of such other resins according to the present invention include, but are not limited to: high density polyethylene, low density polyethylene, ethylene propylene diene monomer (EDPM), thermoplastic elastomer (TPE), acrylonitrile-butadiene-styrene copolymer (ABS), ethylene vinyl acetate copolymer (EVA), ethylene octene polymer elastomer (POE), polyamide, polyester, thermoplastic polyurethane, polylactic acid, silicone rubber.

In the present invention, the mixing ratio of polypropylene and other resin is not particularly limited, and both can be mixed in any ratio and used as the polypropylene base resin of the present invention. The mixture of the polypropylene and other resins is obtained by melt blending.

In the present invention, the polypropylene base resin may be prepared according to various conventional methods, for example, the components of the polypropylene base resin may be prepared separately, and then the prepared components and optionally other additives may be mechanically mixed in a mechanical mixing device according to a certain ratio, and then added to a melt blending device for melt blending. The mechanical mixing device may be, for example, a high-speed stirrer, a kneader, or the like. The melt blending apparatus may be, for example, a twin screw extruder, a single screw extruder, an open mill, an internal mixer, or the like.

According to the invention, the guanidine salt composite antibacterial agent contains a guanidine salt polymer, a zinc salt and/or a copper salt, an anti-migration agent, a nano-scale powder rubber and a dispersing agent, wherein the content of the zinc salt and/or the copper salt is 0.01-40 parts by weight, the content of the anti-migration agent is 0.1-10 parts by weight, the content of the nano-scale powder rubber is 0.5-100 parts by weight and the content of the dispersing agent is 0.1-10 parts by weight based on 100 parts by weight of the guanidine salt polymer.

Preferably, the content of the zinc salt and/or the copper salt is 5-25 parts by weight, the content of the anti-migration agent is 0.5-5 parts by weight, the content of the nanoscale powder rubber is 4.5-50 parts by weight, and the content of the dispersing agent is 0.5-5 parts by weight.

According to the invention, the guanidine salt polymer can be various polyguanidine salts in the technical field of antibiosis, and preferably, the guanidine salt polymer is selected from at least one of inorganic acid salt and/or organic acid salt of polyhexamethylene (di) guanidine and polyoxyethylene guanidine; further preferably at least one selected from the group consisting of polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine phosphate, polyhexamethylene (bis) guanidine acetate, polyhexamethylene (bis) guanidine propionate, polyhexamethylene (bis) guanidine stearate, polyhexamethylene (bis) guanidine laurate, polyhexamethylene (bis) guanidine benzoate and polyhexamethylene (bis) guanidine sulfonate; still more preferably polyhexamethylene (bis) guanidine hydrochloride and/or polyhexamethylene (bis) guanidine propionate.

According to the present invention, the zinc salt and/or copper salt may be selected from various water-soluble zinc salts and/or copper salts, for example, at least one selected from zinc sulfate, zinc nitrate, zinc chloride, zinc acetate, copper sulfate, copper nitrate and copper chloride; preferably an inorganic zinc salt and/or an inorganic copper salt, for example at least one selected from zinc sulfate, zinc nitrate, zinc chloride, copper sulfate, copper nitrate and copper chloride; further preferably zinc sulfate and/or copper sulfate. The addition of zinc salt and/or copper salt can obviously improve the antibacterial performance of the guanidine salt composite antibacterial agent.

In the invention, the addition of the anti-migration agent can effectively improve the water resistance of the guanidine salt polymer in the product, and even if the dosage of the guanidine salt composite antibacterial agent is less, the excellent antibacterial effect can be achieved before and after water boiling. According to the present invention, preferably, the anti-migration agent is a blocked polyisocyanate, and further preferably at least one selected from the group consisting of a phenol-blocked polyisocyanate, a caprolactam-blocked polyisocyanate, and a butanone oxime-blocked polyisocyanate. In the present invention, the blocked polyisocyanate can be obtained commercially, for example, from Colesine

2794XP, bayer BL5140.

The powder rubber in the guanidine salt composite antibacterial agent is beneficial to reducing the water absorption of the guanidine salt composite antibacterial agent during storage, improving the moisture resistance of the guanidine salt composite antibacterial agent and improving the dispersibility of the antibacterial agent, thereby increasing the operability and the use timeliness of the antibacterial agent in practical application. In the invention, the nano-scale powder rubber can be various nano-scale powder rubber particles, preferably at least one of radiation cross-linked fully-vulcanized styrene-butadiene rubber, fully-vulcanized carboxylated styrene-butadiene rubber, fully-vulcanized nitrile-butadiene rubber, fully-vulcanized carboxylated nitrile-butadiene rubber, fully-vulcanized acrylate rubber, fully-vulcanized ethylene vinyl acetate rubber, fully-vulcanized silicon rubber and fully-vulcanized vinylpyridine butadiene rubber; further preferred is fully vulcanized styrene-butadiene rubber and/or fully vulcanized silicone rubber.

According to the invention, the dispersant is used for improving the dispersibility of the antibacterial agent, and can be various dispersants which are conventional in the field, preferably nanoscale inorganic powder, and further preferably at least one selected from nanoscale calcium carbonate, silicon dioxide, montmorillonite, zinc oxide, talcum powder, titanium dioxide, carbon nano tubes, graphene, carbon fibers, boron nitride, zirconium dioxide, wollastonite and zeolite; more preferably nano-sized calcium carbonate and/or nano-sized fumed silica.

According to a preferred embodiment, the preparation method of the guanidine salt compound antibacterial agent comprises the following steps:

a. contacting an aqueous guanidinium polymer solution with an aqueous solution of a zinc salt and/or a copper salt to form a transparent liquid mixture;

b. mixing the liquid mixture obtained in the step a with a latex solution after radiation crosslinking, and then adding an anti-migration agent to obtain a mixture;

c. and c, carrying out spray drying on the mixture obtained in the step b to obtain solid powder, and then mixing the solid powder with a dispersing agent to obtain the guanidine salt composite antibacterial agent.

According to the invention, the mass concentration of the guanidine salt polymer aqueous solution is 10-40%, preferably 15-25%; the mass concentration of the aqueous solution of the zinc salt and/or the copper salt is 15-30%, preferably 20-25%; the mass concentration of the latex solution is 30-40%.

A large number of experiments show that the concentrations of the guanidine salt polymer aqueous solution, the zinc salt and/or copper salt aqueous solution and the latex solution are within the range of the preparation method, so that the guanidine salt composite antibacterial agent can be better prepared. The concentrations of the aqueous solution of the guanidine salt polymer, the aqueous solution of the zinc salt and/or the copper salt and the latex emulsion used in the invention are not too high, otherwise, the uniform stirring is not facilitated, the coagulation phenomenon can also occur, and the subsequent spray drying operation can not be carried out; the concentration is not too low, otherwise, the production efficiency is low, and water resources and energy are wasted. The preparation and mixing operations of the solution are carried out at room temperature, and the spray drying operation can be carried out after mixing, so the preparation method has the advantages of low energy consumption, short time, high efficiency and continuous production.

According to the invention, the spray drying can be carried out in a spray dryer. The mixing of the solid powder and the dispersing agent can be carried out in a high-speed stirrer, and the guanidine salt composite antibacterial agent of the invention is obtained after high-speed stirring and dispersing.

In the present invention, the guanidine salt polymer aqueous solution can be obtained by dissolving a guanidine salt polymer solid in water, or can be directly obtained commercially.

According to the invention, the weight ratio of the guanidine salt polymer in the guanidine salt polymer aqueous solution, the zinc salt and/or the copper salt in the zinc salt and/or copper salt aqueous solution, the solid solution in the latex solution, the anti-migration agent and the dispersing agent is 100: 0.01-40: 0.5-100: 0.1-10; preferably, the weight ratio of the guanidine salt polymer in the guanidine salt polymer aqueous solution, the zinc salt and/or the copper salt in the zinc salt and/or copper salt aqueous solution, the solid solution in the latex solution, the anti-migration agent and the dispersing agent is 100: 5-25: 4.5-50: 0.5-5.

According to the present invention, the latex may be determined according to the type of the finally required powdered rubber, and preferably, the latex is at least one of styrene-butadiene latex, carboxylated styrene-butadiene latex, acrylonitrile-butadiene latex, carboxylated acrylonitrile-butadiene latex, acrylate latex, ethylene vinyl acetate latex, silicone rubber latex and butadiene-styrene-pyridine latex; preferably styrene-butadiene latex and/or silicone rubber latex.

In the present invention, the guanidine salt polymer, the zinc salt and/or copper salt, the anti-migration agent and the dispersant are selected as described above, and thus, they will not be described in detail herein.

According to the invention, because the antibacterial components such as the guanidine salt polymer, the zinc salt and the like are uniformly dispersed in the latex and then are subjected to spray drying, the antibacterial components are more uniformly dispersed in the final product, and the method is also favorable for better dispersing effect of the powdered rubber in the processing process and improving the antibacterial effect.

The guanidine salt composite antibacterial agent has good antibacterial performance, is regular in appearance form, spherical and good in fluidity due to being obtained by spray drying, and can be directly added into plastics, rubber and fibers for use.

According to the present invention, in order to improve the impregnation rate and diffusion rate of the foaming agent and increase the uniformity of cells, the antibacterial polypropylene composition further comprises a cell nucleating agent, wherein the type of the cell nucleating agent can be selected conventionally in the field, for example, the cell nucleating agent can be an inorganic cell nucleating agent or an organic cell nucleating agent, the inorganic cell nucleating agent can be at least one selected from zinc borate, silicon dioxide, talcum powder, calcium carbonate, borax and aluminum hydroxide, and the cell nucleating agent can be obtained from the corners easily obtained from raw materialsFrom the viewpoint of degree, the inorganic cell nucleating agent is particularly preferably talc. Examples of organic type cell nucleating agents include, but are not limited to: glycerol, polyethylene glycol, C ₁₂ -C ₂₃ And hydrophilic compounds such as glycerol esters of fatty acids. The polyethylene glycol is a nonionic water-soluble polymer having a structure obtained by polymerizing ethylene glycol, and the number average molecular weight thereof may be 5 ten thousand or less, preferably 500 to 6000, and more preferably 800 to 4000. In addition, the C ₁₂ -C ₂₃ The glyceride of fatty acid of (a) is preferably at least one of a monoester, a diester, and a triester formed from stearic acid and glycerin. The use of the cell nucleating agent enables easy obtaining of polypropylene expanded beads of high expansion ratio. The cell nucleating agent is preferably glycerin and/or polyethylene glycol, and most preferably glycerin, from the viewpoint of obtaining a polypropylene expanded bead having a high expansion ratio with a small addition amount and having a good degree of fusion of the appearance layer and an excellent appearance when forming an in-mold expanded bead molded body.

In the invention, the guanidine salt composite antibacterial agent can play a role of a foam cell nucleating agent, the addition of the guanidine salt composite antibacterial agent can reduce the using amount of the foam cell nucleating agent, for example, the same foam cell control effect is achieved, and the addition amount of the foam cell nucleating agent can be reduced from 0.2 to 0.1 part by weight. The content of the guanidine salt composite antibacterial agent is 0.05 to 2.0 parts by weight based on 100 parts by weight of the polypropylene base resin, and the content of the foam cell nucleating agent can be 0.01 to 5 parts by weight, preferably 0.01 to 2 parts by weight, and particularly preferably 0.01 to 0.5 part by weight.

According to the present invention, the antioxidant comprises a phenolic antioxidant, a phosphite antioxidant, or a composite antioxidant composed of the two, and specifically, the antioxidant may be selected from at least one of pentaerythrityl tetrakis [ β - (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] (antioxidant 1010), n-octadecyl β - (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076), 2' -methylenebis- (4-methyl-6-tert-butylphenol), 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, tris (2, 4-di-tert-butylphenyl) phosphite, bis (2, 4-di-tert-butylphenol) pentaerythritol diphosphite (antioxidant 626), and bis (2, 6-di-tert-butyl-4-tolyl) pentaerythritol diphosphite.

In addition, the antimicrobial polypropylene composition may contain various other conventional additives commonly used in polypropylene expanded beads, such as light stabilizers, flame retardants, glass fibers, toughening agents, compatibilizers, pigments, coupling agents, dispersants, and the like, in addition to the antioxidant. The types and the contents of the above-mentioned auxiliaries can be selected conventionally in the art, and those skilled in the art can know the types and the contents, and are not described herein again.

According to a second aspect of the present invention, the present invention provides a microporous antibacterial polypropylene foamed sheet material, which is prepared from the antibacterial polypropylene composition.

According to a third aspect of the present invention, the present invention provides a method for preparing a microporous antibacterial polypropylene foamed sheet, the method comprising granulating the antibacterial polypropylene composition, extruding the obtained antibacterial polypropylene granules into a sheet, and foaming, wherein the foaming method is preferably a compression molding foaming method.

In the present invention, the granulation and extrusion into the sheet material can be performed by various methods, and the specific operation process is well known to those skilled in the art.

Specifically, the mould pressing foaming equipment comprises: the system comprises a hydraulic system for providing the die closing pressure, a temperature control system for providing heat, a high-pressure conveying system for providing the supercritical fluid foaming agent, a flat foaming mold, a rapid pressure relief system and a gas recovery system.

The process steps of the mould pressing foaming method are as follows:

(1) A temperature control system providing heat raises the flat foaming mold to a foaming temperature;

(2) Putting the extruded sheet into a flat foaming mold, driving the flat foaming mold to be closed by a hydraulic system, pressurizing the hydraulic system to 15-40MPa, and introducing a supercritical fluid foaming agent into the flat foaming mold by a high-pressure gas conveying system to ensure that the gas pressure reaches 5-30MPa, preferably 10-20MPa;

(3) The supercritical fluid foaming agent diffuses from the surface of the material into the polypropylene composition extruded sheet, and the saturation time required by diffusion is 10-600 minutes, preferably 30-300 minutes;

(4) After the dissolution balance is achieved, the rapid pressure relief system rapidly releases the gas in the flat foaming mold and recovers the gas through the gas recovery system. And opening the die, and foaming the extruded sheet in the die to obtain the microporous antibacterial polypropylene foamed sheet.

The supercritical fluid foaming agent can be supercritical carbon dioxide, supercritical nitrogen or mixed gas of the supercritical carbon dioxide and the supercritical nitrogen in any proportion.

The molding press can be provided with a layer of foaming mold and a plurality of layers of foaming molds.

The foaming temperature is in the temperature range that the polypropylene resin can generate viscoelastic deformation, and for the polypropylene composition, the foaming temperature is 0.1-40 ℃ lower than the melting point of the polypropylene resin, and the preferable foaming temperature is 120-170 ℃.

The pressure relief and mold opening can be realized by firstly relieving the supercritical fluid pressure in the mold to any pressure lower than the saturation pressure through a pressure relief valve and then opening the mold, or by directly opening the mold under the supercritical condition.

In the present invention, the pressures are gauge pressures.

For the microporous antibacterial polypropylene foamed sheet, the volume expansion ratio obtained under the conditions is 2-45 times, the average pore diameter is 1-10 mu m, and the pore density is 1.0 multiplied by 10 ⁶ ～1.0×10 ¹⁵ Per cm ³ 。

According to a fourth aspect of the present invention, the present invention provides a microporous antibacterial polypropylene foamed sheet, which is obtained by cutting and molding the microporous antibacterial polypropylene foamed sheet or the microporous antibacterial polypropylene foamed sheet prepared by the above preparation method.

According to the present invention, the cutting and forming can be performed in various existing foamed plastic cutting and forming machines, and the conditions for cutting and forming the plastic sheet can be selected conventionally in the field, and those skilled in the art can know that the conditions are not described herein again.

For the microporous antibacterial polypropylene foamed sheet, the thickness obtained under the above conditions is a minimum thickness of 0.1mm, preferably a minimum thickness of 0.3mm. The thickness tolerance is 0.01-0.02.

Preferred embodiments of the present invention will be described in more detail below.

In the following examples and comparative examples, the relevant data were obtained according to the following test methods:

(1) Density tester: CPA225D, density annex YDK01, satorius, germany. The test method comprises the following steps: the apparent densities of the polypropylene base resin and the polypropylene foam material were obtained by a drainage method according to the GB/T6343-2009 standard test using a density accessory of a Satorius balance. The foaming ratio of the obtained polypropylene foaming material is calculated by a formula: b = ρ 1/ρ 2, where b is the expansion ratio, ρ 1 is the density of the polypropylene base resin, and ρ 2 is the apparent density of the foamed material.

(2) Scanning electron microscope: XL-30, FEI corporation, USA. The test method comprises the following steps: quenching the foaming material by liquid nitrogen, spraying gold on the section, observing the cell structure inside the foaming material by adopting a Scanning Electron Microscope (SEM), and measuring the cell size by adopting Image Pro Plus software.

(3) Testing the compression strength of the foamed sheet: A50X 25mm sample was cut out from the foamed sheet, and a compression strength test was conducted based on American ASTM standard D3575-08, and a compression test was conducted at a compression rate of 10mm/min to obtain a compression strength at which the molded body was compressed by 50%.

(4) And (3) antibacterial testing: the detection is carried out according to QB/T2591-2003A 'antibacterial plastic antibacterial performance test method and antibacterial effect', and the detection bacteria: escherichia coli (Escherichia coli) ATCC 25922, staphylococcus aureus (Staphylococcus aureus) ATCC 6538.

The sample is soaked in hot water at 50 ℃ for 16h before the antibacterial test. The test procedure was as follows: and (3) sterilizing a sample to be detected by using 75% ethanol, drying the sample, and diluting the strain into a bacterial suspension with a proper concentration by using sterile water for later use. 0.2mL of the bacterial suspension was dropped on the surface of the sample, and a polypropylene film (4.0 cm. Times.4.0 cm) having a thickness of 0.1mm was coated thereon to form a uniform liquid film of the bacterial suspension between the sample and the film. Culturing at 37 deg.C and relative humidity of 90% for 18-24 hr. The bacterial liquid is washed by sterile water, diluted to a proper concentration gradient, and 0.1mL of the diluted bacterial liquid is uniformly coated on a prepared sterile agar culture medium. The culture was carried out at 37 ℃ for 18 to 24 hours, and the results were observed. The negative control was replaced with a sterile plate and the other operations were identical.

Preparation examples 1 to 8 were used to prepare the guanidine salt complex antibacterial agent of the present invention.

Preparation example 1

a. Dissolving 1000.0g of polyhexamethylene guanidine hydrochloride in water to prepare an aqueous solution with the mass concentration of 20%; 50.0g of zinc sulfate is prepared into an aqueous solution with the mass concentration of 25%. 125.0g of styrene-butadiene latex solution is directly used after radiation crosslinking, and the concentration is 40 percent. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, and stirring while adding until the guanidine salt polymer aqueous solution is uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 5.0g of an anti-migration agent a (Colesine) was added to the mixture

2794 XP). d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; the obtained solid powder was transferred to a high-speed stirrer, 5.0g of fumed silica was added as a dispersant, and after high-speed mixing and dispersion, the guanidine salt composite antibacterial agent # 1 of the present invention was obtained, and its electron micrograph is shown in fig. 1, which shows that the guanidine salt composite antibacterial agent of the present invention has a regular appearance and a spherical shape.

Preparation example 2

a. Dissolving 1000.0g of polyhexamethylene guanidine propionate in water to prepare an aqueous solution with the mass concentration of 40%; 100.0g of zinc acetate was prepared into an aqueous solution with a mass concentration of 15%. 150.0g of the nitrile latex solution was used directly after radiation crosslinking, the concentration being 30%. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, stirring while adding until the guanidine salt polymer aqueous solution and the zinc-containing aqueous solution are uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 5.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 15.0g of nano calcium carbonate serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent 2#.

Preparation example 3

a. Dissolving 1000.0g of polyhexamethylene biguanide hydrochloride in water to prepare an aqueous solution with the mass concentration of 10%; 200.0g of zinc nitrate was prepared into an aqueous solution having a mass concentration of 30%. 125.0g of the silicone rubber latex solution was used directly after radiation crosslinking, the concentration being 40%. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, stirring while adding until the guanidine salt polymer aqueous solution and the zinc-containing aqueous solution are uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 5.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 30.0g of talcum powder serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent # 3.

Preparation example 4

a. Dissolving 1000.0g of polyhexamethylene biguanide hydrochloride in water to prepare an aqueous solution with the mass concentration of 25%; 200.0g of zinc chloride is prepared into an aqueous solution with the mass concentration of 20%. 125.0g of the acrylate latex solution were used directly after radiation crosslinking, the concentration being 40%. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, and stirring while adding until the guanidine salt polymer aqueous solution is uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 25.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; transferring the obtained solid powder into a high-speed stirrer, adding 50.0g of zeolite as a dispersing agent, and mixing and dispersing at high speed to obtain the guanidine salt composite antibacterial agent 4# of the invention.

Preparation example 5

a. Dissolving 1000.0g of polyhexamethylene guanidine hydrochloride in water to prepare an aqueous solution with the mass concentration of 20%; 200.0g of copper sulfate was prepared as an aqueous solution having a mass concentration of 25%. 125.0g of styrene-butadiene latex solution is directly used after radiation crosslinking, and the concentration is 40 percent. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing the copper-containing aqueous solution, stirring while adding until the solution is uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 50.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 15.0g of nano calcium carbonate serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent No. 5.

Preparation example 6

a. Dissolving 1000.0g of polyhexamethylene guanidine hydrochloride in water to prepare an aqueous solution with the mass concentration of 20%; 200.0g of copper chloride was prepared as an aqueous solution having a mass concentration of 25%. 625.0g of styrene-butadiene latex solution is directly used after radiation crosslinking, and the concentration is 40%. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing the copper-containing aqueous solution, stirring while adding until the solution is uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the liquid mixture is uniformly mixed. Then, 50.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 30.0g of nano calcium carbonate serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent 6#.

Preparation example 7

a. Dissolving 1000.0g of polyhexamethylene guanidine hydrochloride in water to prepare an aqueous solution with the mass concentration of 20%; 200.0g of zinc sulfate was prepared into an aqueous solution having a mass concentration of 25%. 1250.0g of styrene-butadiene latex solution is used directly after radiation crosslinking, and the concentration is 40 percent. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, and stirring while adding until the guanidine salt polymer aqueous solution is uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the liquid mixture is uniformly mixed. Then, 50.0g of the anti-migration agent a was added to the mixture. d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 50.0g of nano calcium carbonate serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent 7#.

As can be seen from the experimental results, the content of the powdered rubber in the guanidine salt composite antibacterial agent can be up to 60wt% of the antibacterial agent, and the increase of the content of the powdered rubber helps to reduce the moisture absorption during storage, thereby increasing the operability and the use aging property in practical application.

Preparation example 8

The same procedure as in example 1 was followed, except that the anti-migration agent used was anti-migration agent b (bayer BL 5140), to obtain guanidine salt complex antibacterial agent # 8 according to the present invention.

Examples 1 to 12 are provided to illustrate an antibacterial polypropylene composition and a microporous antibacterial polypropylene foamed sheet/sheet according to the present invention.

Example 1

The polypropylene composition provided by the embodiment contains guanidine salt composite antibacterial agent 1#, high melt strength polypropylene, foam cell nucleating agent and processing aid.

Homopolymerized high melt strength polypropylene, brand HMS20Z, produced by China petrochemical and marine refining, and having a melt index of 2.0g/10min (230 ℃,2.16 kg) and a melting point of 160 ℃;

cell nucleating agent, talc;

the processing aid includes antioxidant 1010 (BASF corporation), antioxidant 168 (BASF corporation).

(1) Preparation of polypropylene composition:

the components are weighed and mixed according to the mixture ratio, wherein the HMS20Z accounts for 100 parts by weight, and the preparation example 1 accounts for 1.2 parts by weight; 0.1 part by weight of talcum powder; 0.2 part by weight of antioxidant 1010 and 0.1 part by weight of antioxidant 168 respectively. And then adding the mixture into a high-speed stirrer for uniform mixing, adding the mixed material into a feeder of a double-screw extruder manufactured by W & P company, feeding the material into the double screws through the feeder, keeping the temperature of the screws between 170 and 200 ℃ in the processing process, melting and uniformly mixing the materials through the screws, extruding, granulating and drying to obtain the antibacterial polypropylene random copolymer composition granules.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

drying the polypropylene composition granules prepared in the step (1), mixing the granules by a double-screw extruder, molding the mixture by a die, cooling and cutting the mixture to prepare the polypropylene plate to be foamed with the thickness of 720mm multiplied by 360mm multiplied by 18 mm. The mold, which was installed between the molding presses, was heated to 159 ℃, the polypropylene sheet was placed therein, the molding presses were closed, and the mold was sealed. Introducing 30MPa of supercritical nitrogen into the die, and diffusing the supercritical nitrogen into the polypropylene matrix at 155 ℃ under the condition of 30 MPa. And after the polypropylene foamed plate is saturated for 60min, achieving diffusion balance, reducing the pressure in the die to 12MPa through a pressure relief valve, then opening the die, relieving pressure, foaming, cooling and shaping to obtain the polypropylene foamed plate with the external dimension of 1442mm multiplied by 721mm multiplied by 36 mm. The appearance of the plate is flat and smooth, and the size is uniform. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

and (3) cutting the microporous antibacterial polypropylene foamed plate obtained in the step (2) into a sheet with the thickness of 2mm by using an automatic slicing machine. A sample of 50mm by 50mm was cut out and subjected to an antibacterial test. And (3) soaking a part of sample wafers in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 2

Preparation of the Polypropylene composition, preparation of the microporous antibacterial Polypropylene foamed sheet and preparation of the microporous antibacterial Polypropylene foamed sheet in the exampleThe preparation method is the same as example 1, except that the polypropylene base resin adopted is homo-polymerized high melt strength polypropylene HMS20Z and ethylene propylene diene monomer NORDEL ^TM 3745p (Dow Corp., USA, density 0.880 g/cm) ³ ) The mixture of (1) and (2) is obtained by melt blending, wherein the mixing weight ratio is 8: 2. The properties described in example 1 were performed on the final microporous antimicrobial polypropylene foam and sheet material. Specific results are shown in table 1.

Example 3

The polypropylene composition provided by the embodiment contains a guanidine salt composite antibacterial agent 1#, high melt strength polypropylene, a foam cell nucleating agent and a processing aid.

Random copolymerization high melt strength polypropylene, brand E02ES, produced by Chinese petrochemical and marine refining, with a melt index of 1.5g/10min (230 ℃,2.16 kg), a melting point of 150 ℃;

cell nucleating agents, kaolin;

(1) Preparation of the Polypropylene composition:

the polypropylene composition was prepared as in example 1, except that HMS20Z was used instead of E02ES.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

drying the polypropylene composition granules prepared in the step (1), mixing the granules by a double-screw extruder, molding the mixture by a die, cooling and cutting the mixture to prepare the polypropylene plate to be foamed with the thickness of 720mm multiplied by 360mm multiplied by 18 mm. The mold, which was installed between the molding presses, was heated to 148 ℃, the polypropylene sheet was placed therein, the molding presses were closed, and the mold was sealed. Introducing 15MPa of supercritical carbon dioxide into the die, and diffusing the supercritical carbon dioxide into the polypropylene matrix at 157 ℃ under the condition of 15 MPa. And after the mixture is saturated for 45min, the diffusion balance is achieved, the pressure in the die is reduced to 4MPa through a pressure relief valve, then the die is opened, the pressure is relieved and the foaming is carried out, a foaming plate is popped up, and the polypropylene foaming plate is cooled and shaped to obtain the polypropylene foaming plate with the external dimension of 2402mm multiplied by 1201mm multiplied by 60mm. The plate has flat and smooth appearance and uniform size. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy as shown in figure 1. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

and (3) cutting the microporous antibacterial polypropylene foamed plate obtained in the step (2) into a sheet with the thickness of 0.3mm by using an automatic slicing machine. A sample of 50mm by 50mm was cut out and subjected to an antibacterial test. And (3) soaking a part of sample wafers in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 4

The preparation of the polypropylene composition, the preparation of the microporous antibacterial polypropylene foamed sheet and the preparation of the microporous antibacterial polypropylene foamed sheet in this example are the same as those in example 3, except that the polypropylene base resin used is a mixture of random copolymerization high melt strength polypropylene E02ES and Low Density Polyethylene (LDPE) 2102TN26 (produced by Chinese petrochemicals, qilu petrochemical, having a melt index of 2.2g/10min (190 ℃,2.16 kg), a melting point of 135 ℃) and POE 9061 (produced by Exxon Mobil, having a melt index of 0.5g/10min (190 ℃,2.16 kg)), the weight ratio of the mixture is 8.5: 1.0: 0.5, and the mixture is obtained by melt blending. The properties described in example 3 were performed on the final microporous antimicrobial polypropylene foam and sheet material. Specific results are shown in table 1.

Example 5

Random copolymerization high melt strength polypropylene, brand WB140, produced by northern Europe chemical industry, with melt index of 2.1g/10min (230 ℃,2.16 kg), melting point of 158 ℃;

cell nucleating agents, ultrafine calcium carbonate;

(1) Preparation of polypropylene composition:

the polypropylene composition was prepared as in example 1, except that WB140 was used instead of E02ES.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

drying the polypropylene composition granules prepared in the step (1), mixing the granules by a double-screw extruder, molding the mixture by a die, cooling and cutting the mixture to prepare the polypropylene plate to be foamed with the thickness of 720mm multiplied by 360mm multiplied by 18 mm. The mold, which was installed between the molding presses, was heated to 155 ℃, the polypropylene sheet was placed in it, the molding presses were closed, and the mold was sealed. Introducing 10MPa of supercritical carbon dioxide into the die, and diffusing the supercritical carbon dioxide into the polypropylene matrix at 155 ℃ under the condition of 10 MPa. And after the mixture is saturated for 180min, the dispersion balance is achieved, then the mould is opened, the pressure is released, the foaming is carried out, and the cooling and the shaping are carried out, so as to obtain the polypropylene foaming plate with the external dimension of 2002mm multiplied by 1001mm multiplied by 51 mm. The plate has flat and smooth appearance and uniform size. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

and (3) cutting the microporous antibacterial polypropylene foamed plate obtained in the step (2) into a sheet with the thickness of 1mm by using an automatic slicing machine. A sample of 50mm by 50mm was cut out and subjected to an antibacterial test. And (3) soaking a part of sample wafers in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 6

The polypropylene composition provided by the embodiment contains guanidine salt composite antibacterial agent 3#, high melt strength polypropylene, foam cell nucleating agent and processing aid.

(1) Preparation of the Polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt complex antibacterial agent # 3 was added in an amount of 0.5 parts.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

the microporous antibacterial polypropylene foamed sheet was prepared in the same manner as in example 3 to obtain a polypropylene foamed sheet having an external dimension of 2402mm × 1201mm × 60mm. The appearance of the plate is flat and smooth, and the size is uniform. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

the microporous antibacterial polypropylene foamed sheet was prepared as in example 3, and cut into a sheet having a thickness of 0.3mm. Cut to obtain a sample of 50mm by 50mm and subjected to an antibacterial test. And (3) soaking part of the sample wafer in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 7

The polypropylene composition provided by this embodiment contains guanidine salt composite antibacterial agent 5#, high melt strength polypropylene, cell nucleating agent and processing aid.

(1) Preparation of the Polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt complex antibacterial agent 5# was added in an amount of 0.3 parts.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

the microporous antibacterial polypropylene foamed sheet was prepared in the same manner as in example 3 to obtain a polypropylene foamed sheet having an external dimension of 2402mm × 1201mm × 60mm. The plate has flat and smooth appearance and uniform size. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

the microporous antibacterial polypropylene foamed sheet was prepared as in example 3, and cut into a sheet having a thickness of 0.3mm. A sample of 50mm by 50mm was cut out and subjected to an antibacterial test. And (3) soaking a part of sample wafers in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 8

The polypropylene composition provided by this embodiment contains guanidine salt composite antibacterial agent 2#, high melt strength polypropylene, cell nucleating agent and processing aid.

(1) Preparation of polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt complex antibacterial agent 1# was replaced with the guanidine salt complex antibacterial agent 2# of the same weight.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

Example 9

The polypropylene composition provided by the embodiment contains guanidine salt composite antibacterial agent 4#, high melt strength polypropylene, foam cell nucleating agent and processing aid.

(1) Preparation of the Polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt complex antibacterial agent 1# was replaced with the guanidine salt complex antibacterial agent 4# of the same weight.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

the microporous antibacterial polypropylene foamed sheet was prepared in the same manner as in example 3 to obtain a polypropylene foamed sheet having external dimensions of 2402mm X1201 mm X60 mm. The plate has flat and smooth appearance and uniform size. The foaming ratio was measured. The internal cell morphology was analyzed by scanning electron microscopy. It was subjected to a compression test. The properties are shown in Table 1.

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

Example 10

The polypropylene composition provided by this embodiment contains guanidine salt composite antibacterial agent 6#, high melt strength polypropylene, cell nucleating agent and processing aid.

(1) Preparation of polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt composite antibacterial agent 1# was replaced with the guanidine salt composite antibacterial agent 6# having the same weight.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

the microporous antibacterial polypropylene foamed sheet was prepared as in example 3, and cut into a sheet having a thickness of 0.3mm. A sample of 50mm by 50mm was cut out and subjected to an antibacterial test. And (3) soaking part of the sample wafer in hot water at 50 ℃ for 16 hours before the antibacterial test. The properties are shown in Table 1.

Example 11

The polypropylene composition provided by the embodiment contains guanidine salt composite antibacterial agent 7#, high melt strength polypropylene, foam cell nucleating agent and processing aid.

(1) Preparation of polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt composite antibacterial agent 1# was replaced with a guanidine salt composite antibacterial agent 7# of the same weight.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

Example 12

The polypropylene composition provided by this embodiment contains guanidine salt composite antibacterial agent 8#, high melt strength polypropylene, cell nucleating agent and processing aid.

(1) Preparation of polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the guanidine salt complex antibacterial agent 1# was replaced with the guanidine salt complex antibacterial agent 8# of the same weight.

(2) Preparing a microporous antibacterial polypropylene foamed plate:

(3) Preparing a microporous antibacterial polypropylene foamed sheet:

Comparative example 1

The polypropylene composition provided by the comparative example contains guanidine salt composite antibacterial agent 1#, polypropylene, foam cell nucleating agent and processing aid.

Random copolymer polypropylene, designation W331, manufactured by Singapore TPC corporation, has a melt index of 7.0g/10min (230 ℃,2.16 kg). The melting point is 146 ℃;

cell nucleating agent, kaolin;

(1) Preparation of the Polypropylene composition:

a polypropylene composition was prepared as in example 3, except that the polypropylene E02ES therein was replaced with the same weight of W331.

(2) Preparation of antibacterial polypropylene expanded beads:

and (2) adding the polypropylene composition obtained in the step (1) and auxiliary agents such as dispersion medium deionized water, surfactant sodium dodecyl benzene sulfonate, dispersant kaolin, dispersion reinforcing agent aluminum sulfate and the like into an autoclave at one time, and uniformly mixing, wherein the dosage of the dispersion medium is 3000 parts by weight, the dosage of the surfactant is 0.3 part by weight, the dosage of the dispersant is 4.5 parts by weight and the dosage of the dispersion reinforcing agent is 0.15 part by weight relative to 100 parts by weight of polypropylene composition granules.

The autoclave cover was closed tightly, residual air in the autoclave was purged with carbon dioxide, and then carbon dioxide was continuously fed into the autoclave, heating was started and the pressure in the autoclave was preliminarily adjusted until it was stabilized, and then the autoclave was stirred at a stirring speed of 100rpm to heat the temperature in the autoclave to 224 ℃.

The pressure in the autoclave was adjusted to 5MPa and the temperature was raised to 224.5 ℃ at an average heating rate of 0.1 ℃/min, followed by continuous stirring at the above pressure and temperature for 0.5 hour.

The discharge port of the autoclave was opened to discharge the contents of the autoclave into a collecting tank to obtain expanded beads, and carbon dioxide gas was fed while discharging so that the pressure in the autoclave was maintained at about the foaming pressure before all the particles were completely foamed and entered the collecting tank.

Collecting the beads, dewatering, drying, and sieving with sieves with pore diameter of 3.35mm and 2.8mm to obtain antibacterial polypropylene foamed beads with particle diameter of 2.8-3.35 mm.

(3) Preparation of antibacterial polypropylene foamed bead formed sheet

And (3) molding the antibacterial polypropylene expanded beads obtained in the step (2) by using a molding machine (Kurtz T-Line produced by KurtzErsa, germany, the same applies below) under the pressure of 0.66MPa, and curing the obtained molded body for 24 hours under the conditions that the temperature is 100 ℃ and the pressure is standard atmospheric pressure to obtain a molded plate. The volume of the plate is 1000mm by 60mm. The performance parameters of the molded product, such as foaming ratio, cell size, compressive strength, antibacterial effect, etc., are shown in Table 1.

(4) Preparing an antibacterial polypropylene foamed sheet:

the antibacterial polypropylene expanded bead molded plate obtained in the step (3) cannot obtain a uniform and complete large-area sheet by adopting the sheet preparation method of the embodiment 3.

Comparative example 2

(1) Preparation of polypropylene composition:

the polypropylene composition was prepared as in example 3.

(2) Preparation of antibacterial polypropylene foamed extrusion foaming sheet material

And (2) putting the polypropylene composition obtained in the step (1) into a hopper of an extruding machine, heating the extruding machine to 150-280 ℃, smelting a polypropylene foaming material, preferably 160-180 ℃, smelting particles, extruding plasticized polypropylene resin to a T-shaped head die at 150-280 ℃, preferably 160-180 ℃ at the screw rotation speed of 15-180rpm, flowing into a gap between two rollers of a plate extruding machine set, rolling into a sheet material, naturally cooling to room temperature, and cutting into a sheet material with a certain specification as required to obtain the finished product of the antibacterial polypropylene foaming sheet material. The width of the plate is 1500mm, the thickness is 20mm, can cut into arbitrary length, this comparative example selects 3000mm. The performance parameters of the extruded foamed sheet such as foaming multiplying power, bubble size, compressive strength, antibacterial effect and the like are tested and shown in table 1.

(3) Preparing an antibacterial polypropylene foamed sheet:

the antibacterial polypropylene foamed extrusion foaming sheet material obtained in the step (2) adopts the sheet material preparation method of the embodiment 3, and cannot obtain a uniform and complete large-area sheet material.

Comparative example 3

The guanidine salt composite antibacterial agent 1# in example 3 was replaced with polyhexamethylene biguanide hydrochloride in an equal weight ratio, the other procedures were the same as in example 3, and the finally prepared microporous antibacterial polypropylene foam and sheet material were subjected to the properties described in example 3. Specific results are shown in table 1.

Comparative example 4

The guanidine salt composite antibacterial agent 3# in example 6 was replaced with polyhexamethylene biguanide hydrochloride in an equal weight ratio, the other procedures were the same as in example 6, and the finally prepared microporous antibacterial polypropylene foam and sheet material were subjected to the properties described in example 3. Specific results are shown in table 1.

Comparative example 5

The guanidine salt composite antibacterial agent No. 5 in the example 7 is replaced by polyhexamethylene biguanide hydrochloride with the same weight ratio, other steps are the same as the example 3, and the performances of the microporous antibacterial polypropylene foam and sheet material prepared finally are performed according to the performances in the example 3. Specific results are shown in table 1.

Comparative example 6

The guanidine salt composite antibacterial agent 1# in example 3 was removed, the other steps were the same as in example 3, and the properties described in example 3 were performed on the finally prepared microporous blank polypropylene foamed and sheet material. Specific results are shown in table 1.

TABLE 1

The data show that the microporous antibacterial polypropylene foaming plate/sheet has a good antibacterial effect, uniform and fine foam holes, controllable foaming multiplying power and high compression strength, and is easy to prepare into a foaming sheet with random thickness. Example 3 the cell structure of the sample section is shown in figure 1.

Example 3 compares with comparative example 1 and shows that, for the polypropylene composition which is subjected to the guanidine salt composite antibacterial agent, a high-rate foaming plate with excellent antibacterial performance can be obtained through kettle pressure foaming and secondary forming. But the area of the foaming plate is small due to the limitation of the secondary forming die; and the large cell structure inside the beads (the cell structure in comparative example 1 is shown in figure 2) and the beads are adhered to each other, so that the foamed sheet cannot be cut into sheets smoothly.

Example 3 compares with comparative example 2 and demonstrates that a large-area foamed sheet having excellent antibacterial performance can be obtained by extrusion foaming of the polypropylene composition having undergone the guanidine salt complex antibacterial agent. However, the foaming ratio is low, a foamed sheet with a high ratio cannot be obtained, the pore diameter of the cells is larger, the opening ratio is high (the cell structure of the comparative example 2 is shown in figure 3), and the foamed sheet cannot be smoothly cut into sheets.

The comparison result of the embodiment 3 and the comparative example 3 shows that the guanidine salt composite antibacterial agent not only improves the antibacterial effect, but also has better water resistance, and the antibacterial effect of the antibacterial plastic before and after water boiling is better than that of pure polyhexamethylene guanidine hydrochloride.

The results of example 6 and comparative example 4 show that the guanidine salt complex antibacterial agent still has a better antibacterial effect after the dosage of the guanidine salt complex antibacterial agent is reduced, the water resistance after poaching is reduced, but the antibacterial effect of the antibacterial plastic before and after poaching is better than that of pure polyhexamethylene biguanide hydrochloride.

The results of comparison between example 7 and comparative example 5 show that the anti-migration agent significantly improves the water resistance of the guanidine salt composite antibacterial agent, and even if the amount of the guanidine salt composite antibacterial agent is small, the antibacterial effect before and after poaching can be better, compared with the antibacterial effect of the antibacterial plastic before and after poaching which is better than that of pure polyhexamethylene biguanide hydrochloride.

The results of comparing example 3 with comparative example 6 show that the microcellular antibacterial foamed material obtained in example 3 has no significant difference in expansion ratio, mechanical properties and processability, compared with the microcellular foamed material prepared from the blank matrix polypropylene which is not modified by the antibacterial agent. The antibacterial agent has little influence on the foaming performance and the mechanical property of the matrix polypropylene resin.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. The antibacterial polypropylene composition is characterized by comprising polypropylene base resin, a guanidine salt composite antibacterial agent and an auxiliary agent, wherein the auxiliary agent comprises a foam cell nucleating agent and an antioxidant, the content of the guanidine salt composite antibacterial agent is 0.05-2.0 parts by weight, the content of the foam cell nucleating agent is 0.01-10 parts by weight and the content of the antioxidant is 0.01-10 parts by weight based on 100 parts by weight of the polypropylene base resin;

the guanidine salt composite antibacterial agent comprises a guanidine salt polymer, zinc salt and/or copper salt, an anti-migration agent, nano-scale powder rubber and a dispersing agent, wherein the zinc salt and/or copper salt content is 0.01-40 parts by weight, the anti-migration agent content is 0.1-10 parts by weight, the nano-scale powder rubber content is 0.5-100 parts by weight, and the dispersing agent content is 0.1-10 parts by weight, based on 100 parts by weight of the guanidine salt polymer;

the guanidine salt composite antibacterial agent is obtained by spray drying.

2. The antibacterial polypropylene composition according to claim 1, wherein the guanidinium complex antimicrobial agent is present in an amount of 0.05 to 1.5 parts by weight, the foam cell nucleating agent is present in an amount of 0.01 to 0.5 parts by weight, and the antioxidant is present in an amount of 0.01 to 5 parts by weight, based on 100 parts by weight of the polypropylene base resin.

3. The antimicrobial polypropylene composition according to claim 1 or 2, wherein the polypropylene base resin comprises polypropylene or a mixture of polypropylene and other resins;

the polypropylene is homopolymerized polypropylene and/or random copolymerization polypropylene.

4. The antimicrobial polypropylene composition of claim 3, wherein the random copolymer polypropylene is selected from one or more of ethylene propylene random copolymer polypropylene, ethylene propylene random copolymer polypropylene, block copolymer polypropylene, and impact copolymer polypropylene.

5. The antimicrobial polypropylene composition according to claim 3, wherein the polypropylene has a melt index MFR of 0.1 to 3g/10min at 230 ℃ under a load of 2.16kg, a molecular weight distribution Mw/Mn =4 to 20, and a polymer dispersion index of 5.0 to 16.0.

6. The antimicrobial polypropylene composition of claim 3, wherein the polypropylene is a high melt strength polypropylene.

7. The antimicrobial polypropylene composition of claim 3, wherein the other resin is one or more of high density polyethylene, low density polyethylene, ethylene propylene diene monomer, thermoplastic elastomer, acrylonitrile-butadiene-styrene copolymer, ethylene vinyl acetate copolymer, ethylene octene polymer elastomer, polyamide, polyester, thermoplastic polyurethane, polylactic acid, and silicone rubber.

8. The antimicrobial polypropylene composition according to claim 1, wherein the zinc salt and/or the copper salt is contained in an amount of 5 to 25 parts by weight, the anti-migration agent is contained in an amount of 0.5 to 5 parts by weight, the nano-sized powder rubber is contained in an amount of 4.5 to 50 parts by weight, and the dispersant is contained in an amount of 0.5 to 5 parts by weight.

9. The antimicrobial polypropylene composition according to claim 8, wherein the guanidine salt polymer is at least one selected from the group consisting of inorganic and/or organic acid salts of polyhexamethylene (bis) guanidine, and polyoxyethylene guanidine.

10. The antimicrobial polypropylene composition of claim 9, wherein the guanidine salt polymer is selected from at least one of polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine phosphate, polyhexamethylene (bis) guanidine acetate, polyhexamethylene (bis) guanidine propionate, polyhexamethylene (bis) guanidine stearate, polyhexamethylene (bis) guanidine laurate, polyhexamethylene (bis) guanidine benzoate, and polyhexamethylene (bis) guanidine sulfonate.

11. The antimicrobial polypropylene composition according to claim 10, wherein the guanidine salt polymer is polyhexamethylene (bis) guanidine hydrochloride and/or polyhexamethylene (bis) guanidine propionate.

12. The antimicrobial polypropylene composition according to claim 8, wherein the zinc salt and/or the copper salt is an inorganic zinc salt and/or an inorganic copper salt.

13. The antimicrobial polypropylene composition of claim 12, wherein the zinc salt and/or the copper salt is at least one selected from zinc sulfate, zinc nitrate, zinc chloride, copper sulfate, copper nitrate and copper chloride.

14. The antimicrobial polypropylene composition of claim 13, wherein the zinc salt and/or copper salt is zinc sulfate and/or copper sulfate.

15. The antimicrobial polypropylene composition of claim 8, wherein the anti-migration agent is a blocked polyisocyanate.

16. The antimicrobial polypropylene composition of claim 15, wherein the anti-migration agent is selected from at least one of phenol blocked polyisocyanate, caprolactam blocked polyisocyanate, and butanone oxime blocked polyisocyanate.

17. The antibacterial polypropylene composition according to claim 8, wherein the nano-sized powder rubber is at least one of fully vulcanized styrene-butadiene rubber, fully vulcanized carboxylated styrene-butadiene rubber, fully vulcanized nitrile rubber, fully vulcanized carboxylated nitrile rubber, fully vulcanized acrylate rubber, fully vulcanized ethylene vinyl acetate rubber, fully vulcanized silicone rubber and fully vulcanized vinylpyridine butadiene rubber which are radiation-crosslinked.

18. The antimicrobial polypropylene composition according to claim 17, wherein the nano-sized powder rubber is a radiation crosslinked fully vulcanized styrene-butadiene rubber and/or a fully vulcanized silicone rubber.

19. The antimicrobial polypropylene composition of claim 8, wherein the dispersant is a nano-sized inorganic powder.

20. The antimicrobial polypropylene composition of claim 19, wherein the dispersing agent is selected from at least one of nano-sized calcium carbonate, silica, montmorillonite, zinc oxide, talc, titanium dioxide, carbon nanotubes, graphene, carbon fibers, boron nitride, zirconium dioxide, wollastonite, and zeolite.

21. The antimicrobial polypropylene composition according to claim 20, wherein the dispersant is nano-sized calcium carbonate and/or nano-sized fumed silica.

22. The antibacterial polypropylene composition according to any one of claims 8 to 21, wherein the preparation method of the guanidine salt composite antibacterial agent comprises the following steps:

a. contacting an aqueous solution of a guanidinium polymer with an aqueous solution of a zinc salt and/or a copper salt to form a transparent liquid mixture;

c. c, spray drying the mixture obtained in the step b to obtain solid powder, and then mixing the solid powder with a dispersing agent to obtain the guanidine salt composite antibacterial agent;

wherein the mass concentration of the aqueous solution of the guanidine salt polymer is 10-40%; the mass concentration of the aqueous solution of the zinc salt and/or the copper salt is 15 to 30 percent; the mass concentration of the latex solution is 30-40%;

the latex is determined according to the type of the nanoscale powdered rubber.

23. The antimicrobial polypropylene composition of claim 22, wherein the latex is at least one of a styrene-butadiene latex, a carboxylated styrene-butadiene latex, a nitrile-butadiene latex, a carboxylated nitrile-butadiene latex, an acrylate latex, an ethylene vinyl acetate latex, a silicone rubber latex, and a pyridine styrene-butadiene latex.

24. The antimicrobial polypropylene composition of claim 23, wherein the latex is styrene-butadiene latex and/or silicone rubber latex.

25. The antimicrobial polypropylene composition according to claim 22, wherein the aqueous solution of the guanidinium polymer has a mass concentration of 15-25%.

26. The antimicrobial polypropylene composition according to claim 22, wherein the aqueous solution of the zinc salt and/or the copper salt has a mass concentration of 20% to 25%.

27. The antimicrobial polypropylene composition according to claim 1 or 2, wherein the foam cell nucleating agent is selected from at least one of zinc borate, silica, talc, calcium carbonate, borax, and aluminum hydroxide.

28. The antimicrobial polypropylene composition of claim 27, wherein the foam cell nucleating agent is talc.

29. A microporous antibacterial polypropylene foamed sheet is characterized in that the microporous antibacterial polypropylene foamed sheet is prepared from the antibacterial polypropylene composition as claimed in any one of claims 1 to 28.

30. A method for preparing a microporous antibacterial polypropylene foamed sheet, which is characterized by comprising the steps of granulating the antibacterial polypropylene composition as claimed in any one of claims 1 to 28, extruding the obtained antibacterial polypropylene particles into a sheet, and foaming, wherein the foaming method is preferably a die-pressing foaming method.

31. A microporous antibacterial polypropylene foamed sheet is characterized in that the microporous antibacterial polypropylene foamed sheet is obtained by cutting and molding the microporous antibacterial polypropylene foamed sheet as claimed in claim 29 or the microporous antibacterial polypropylene foamed sheet prepared by the preparation method as claimed in claim 30.